Reuters –A wealthy New York socialite was sentenced to 18 years in prison on Thursday after being convicted of killing her young autistic son at a luxury Manhattan hotel room in 2010.

Gigi Jordan, 54, was convicted of first-degree manslaughter in November after admitting that she administered an overdose of prescription pills to 8-year-old Jude Mirra at the posh Peninsula Hotel on Fifth Avenue, using a crusher and syringe.

Jordan's attorneys argued throughout the two-month trial that she had killed the boy in an act of mercy to prevent the boy's biological father from sexually abusing him, a scenario that prosecutors said was based on fiction.

Judge Charles Solomon of the state Supreme Court in Manhattan handed down a sentence that was close to the maximum of 25 years in prison under New York guidelines, saying he was mystified by the mother's lack of remorse.

"It's very difficult for me to understand the defendant," Solomon said. "I certainly would think that I would hear something from the defendant expressing remorse about what she did - something."

In a 30-minute statement read to the court, Jordan appealed for leniency and again said she had been acting in her son's best interests.

"I love Jude more than anything in this world," the former pharmaceuticals executive and self-made millionaire said in a 30-minute statement. "I believe that he lived and died in unbelievable agony."

At her trial last year, the jury accepted the defense's claim that Jordan had acted under extreme emotional distress, finding her guilty of manslaughter rather than the top murder charge sought by prosecutors.

Even though Mirra was unable to express himself well, Jordan's attorneys argued, he had told his mother that he was being sexually abused by his father, Emil Tzekov.

Tzekov, a yoga instructor who became Jordan's second ex-husband, has denied the accusations.

Jordan said she feared she would be unable to protect her boy because her first husband, Philadelphia businessman Raymond Mirra Jr., planned to have her killed or institutionalized, and Tzekov would gain custody of her son.

Prosecutors argued that Jordan carefully planned the death of her son after traveling the country to find a cure for his autism. They said that Jordan killed her son because she could not accept that he was disabled and she could not fix his medical condition.

Outside of court, Jordan's attorney, Norman Siegel, expressed disappointment with the sentence and said Jordan would appeal.